1. Reservation of Copyright
This patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent, as it appears in the U.S. Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
2. Field of the Invention
The present invention, in certain respects, relates to wireless communication systems. Other aspects of the invention relate to systems and methods for augmenting existing cellular base station systems and for implementing cellular base station systems.
3. Description of Background Information
Existing and operational base stations for cellular and personal communication systems (PCS) typically comprise antenna arrangements located at the top of a mast or building. Some of these antenna arrangements utilize diversity antennas arrangements to enhance the performance of the base station by, e.g., combating the deleterious effects of multi-path propagation, such as multi-path fading and dispersion. The types of diversity employed may include, e.g., one or a combination of space diversity, phase diversity, frequency diversity, polarization diversity, and time diversity. Some of those existing/operational antenna arrangements may include a first (main) antenna array of co-located antenna elements and a second (diversity) antenna array (or individual antenna element) located at a distance from the first antenna array. The main antenna array may include antenna elements serving as both transmit and receive antennas. The diversity antenna array may include only receive antenna elements. Either or both the main antenna array and the diversity antenna array may be passive in that the antenna elements are not coupled to proximate amplifiers also provided at the top of the mast/building.
Thus, there is a need to augment existing base station antenna setups such as these. For example, existing/operational base stations would benefit by rendering their receive antenna elements active, i.e., by installing low noise amplifiers (LNA) at the top of the mast of a building, rather than only at the bottom of the mast or building. Alternatively or in conjunction with the installation of the LNAs, the transmit elements may be rendered active by installing linearized power amplifiers (LPA) positioned also at the top a building. This will provide certain advantages, including reducing cabling and power consumption costs associated with carrying signals up and down the mast or building. These base station antenna setups may also need augmentation or modification to facilitate a change in cellular technologies, e.g., adding code division multiple access (CDMA) capabilities to a base station using the Advance Mobile Phone Service (AMPS) or Global System for Mobile (GSM) standard or changing the base station altogether for use in a new scheme, e.g., CDMA.
There is also a need to add antenna functionality (e.g., to accommodate new cellular technologies and/or to enhance performance over the forward and reverse links) without adding antenna arrays that may take up additional space, or be considered as additional antenna arrangements (which may be a violation of local laws, regulations or ordinances).
There is a further need for novel and beneficial ways of addressing these issues, and others, in the implementation of cellular base station systems, and more particularly in the implementation of communication sites serving limited coverage areas, such as cells and sectors.